The overall objective of this research is to discover, study and establish novel control mechanisms for the regulation of anabolic and catabolic enzymes, and to analyze the physiochemical bases for the regulatory interactions between enzyme and effector molecules. In this context we are investigating the structure of homoserine dehydrogenase and the different conformational states of the enzyme in the presence of allosteric ligands. A separate aspect of our study involves the elucidation of the mechanism of catabolite inactivation by intermediary metabolites of the inducible biodegraditive threonine dehydratase of Escherichia coli. BIBLIOGRAPHIC REFERENCES: Datta, P. (1976) Amino Acid Biosynthesis, in the Photosynthetic Bacteria (Clayton, R. K. and Sistrom, W. r., eds) Plenum Press, New York (in press).